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Wednesday, October 28, 2009

So, because of a lot of moving around and reshuffling of stuff at work, I was reintroduced to some old photographic plates of echinoderms from taxonomic monographs published by Smithsonian scientists from the early 20th Century.

These days, most people take pictures and can manipulate the images with computers and then electronically transfer those images into document files where they get published and so forth. A fairly paper free process (if you don't count the final result anyway!)

But as recently as 10 years ago, pictures in scientific monographs were done by physically mounting photographs onto heavy cardboard plates.

Usually, these plates are thrown away after publication, but sometimes they get saved and one gets a real feel of just how different times were before Photoshop and the Internet.

Here are a bunch of those plates, complete with instructions, possibly from the original author Walter K. Fisher himself!

Christian studies fossil echinoderms, especially sea urchins and sea stars and put me onto a new short paper he's written in Arbeitskreis Palaontologie Hannover 37: 92-97! Most of the pics featured today are courtesy of his article!

But...WHAT? You didn't realize that there was such a thing as starfish FOSSILS?

Starfish, like other echinoderms are composed of thousands (maybe even hundreds of thousands) of individual calcium carbonate pieces (called ossicles or plates)! So, when they die, those pieces often get scattered into the sediment or the water or etc.

That is why starfish ossicles are SO rare. When they die, these pieces scatter very easily and they fail to preserve over time.

BUT, sometimes we get lucky! Those pieces get preferentially preserved, sometimes while they are still connected together, articulated into large chunks or EVEN the complete animal!

So, in this case, we have pieces that clue us in to one of the most enigmatic of fossil echinoderms! The Sphaerasteridae! An engimatic group of asteroids from the Jurassic!

While dinosaurs were trying to figure out how to roam the Earth, these guys were happily sitting around in the seas of the Mesozoic!

Initially, the pieces recovered were like this:

(Courtesy & copyright of Christian Neuman in APH 37)

You often recover MANY different pieces. Here we have fragments of Sphaeraster punctatus.More precisely..you get either individual pieces (i.e., individual plates) or a "chunk" of the animal that looks like this.

(Courtesy of Christian Neuman in APH 37)

Eventually, you have enough different fragments, pieces, and etc that you can make a guess as to what the original animal looked like.

Starfish paleontology is a LOT like dinosaur paleontology or assembling an airplane model kit without the instructions! You've got a bunch of pieces and you have to reassemble them into what looks like the right shape!

So..what you've get here..VOILA!! A reconstruction of Sphaeraster punctatus (described by Schondorf in 1906!).

(Courtesy of Christian Neuman in APH 37)

It was weird but not really that big..about 75 mm across from left to right. Now bear in mind this is a RECONSTRUCTON. The fossils aren't nearly as nice as this. But it gives you SOME idea of what it looked like.

So, what did this odd-looking thing do when it was alive?? One of the most useful ideas for interpreting these fossils and putting them back together is a concept in paleonotology-indeed ALL of Geology-called Uniformitarianism!

Basically, this is the idea is that a lot of the physical processes and relationships that happened in Earth's past are generally the SAME as they are today. So, we look for critters that appear SIMILAR today... Because its possible the same physical forces may have influenced their appearance and body shape (and giving us insight into Sphaeraster!).

and while, this is plausible, it should be noted that NOTHING is known about these critters. So, maybe its not a podospherasterid either..? We have some AMAZING body shapes and morphology but we have very little biology to match it up with!

Where does that leave us??

Believe it or not, this is it. This is practically our total state of our knowledge of these animals. These beasts fall into the category "about which, little is known..."

It is a pretty curious place where Paleontology and Deep-sea Taxonomy converge!

Both involve specimens (often damaged) with unusual shapes or structures which have been subjects of attempted "interpretation".

Both often involve bizarre mophologies without any direct observation of ecology or even fundamental life mode.

Both subjects usually involve rarely encountered animals which only exceptionally are discovered intact!

So..from here? What do we need? Maybe the talents of Leonard Nimoy on his "In Search of" show, to help discover some of these weird and rare animals?? (cause they sure are a LOT harder to find then the Loch Ness Monster!)Fantastic. BUT real. :-)

Thursday, October 15, 2009

1. First...I was helping Dr. Margo Edwards at the Hawaii Mapping Research Group identify brisingid starfishes for a project involving high school students mapping these neat animals south of Pearl Harbor, Hawaii. Here we have (above) a cluster that Margo calls "Mother Brisinga"... (although, this may or may not be Brisinga..)

For example...this little guy is Linckia multifora, a small fissiparous ophidiasterid. Widespread throughout the Indo-Pacific area..This is another very common member of the Indo-Pacific echinoderm fauna..the sea urchin Echinometra, probably E. mathaei but species for this genus are difficult to tell from pictures..and finally, what looks like Diadema to me..with species hard to call from a picture..and finally 3. MOVING!!! Nothing terribly dramatic..but I have been relocated to a new office just down the hall!!!Similar to both of that Diadema (or that Echinometra) I had gotten pretty entrained in my office....With LOTS of papers and stuffs to move!!But the new office is worth it!and thanks to Daniel Brown at Biochemical Soul for providing some of the new decor in my office!! (note that the poster also shows the phylogenetic relationships of the extant taxa!!) Keen! You can buy the poster from Zazzle..here!A GREAT view of the National Museum of American History and the WA monument from my desk!There will be more!! Now that things are getting back to normal.....

But here was a new GENUS and SPECIES that was easily one foot across (=0.3 meter) and about 4-5 inches (~0.1 m) THICK. It was ENORMOUS.

How had such a LARGE starfish evaded description for so long??? Apparently, this particular depth range had been inaccesible to the two conventional types of collection gear-trawl nets and SCUBA gear. The "sub-reef" zone was inaccessible to trawl nets and too deep for conventional SCUBA gear. With the advent of submersibles and deep-diving type "re-breather" gear , scientists could suddenly access a part of the ocean that had previously been poorly understood. The first specimen was sent to me by Pat and Lori Colin, the biologists at the Coral Reef Research Foundation in Koror Palau, which they had collected their specimen using "re-breather" SCUBA type gear.

I had NEVER seen anything like it before.After that initial specimen I started my PhD and ended up surveying museums all around the world and discovered TWO more of these animals during my travels..

In Hawaii, I discovered the second-known specimen in a 10 gallon bucket that had been in storage since the 1980s. If it were not for the lack of air-conditioning, I would not have been fiddling with the floor fan and discovered the bucket that was sitting underneath it!

Oddly enough, this specimen had also been collected in Enewetok by Pat Colin!

Years later in Europe, I discovered a second dried specimen from the southern Indian Ocean on a specimen shelf among starfish that had been stored in a marine biology laboratory in Belgium! I began to describe the animal in detail.The specimen actually had to be x-rayed so I could get some idea of what it looked like The animal's skeleton was almost COMPLETELY reduced. Most of the animal was made up of a thick, smooth meat that was criss-crossed with channels that opened into the body cavity and opened out to the body surface.

There was almost NOTHING of the externally expressed skeleton that one would normally use to identify it!

Oreasterids are a group of widespread tropical starfish which have heavily built up skeletons. Familiar members of the Oreasteridae include genera, such as Culctia and Protoreaster, which I have written about in the past.

The paper (Kogure et al. 2009. Journal of the Biogeographical Society of Japan 11: 73-76) documents a substantial range extension of this species from Enewetok, Palau, and the southern Indian Ocean to Japan and American Samoa!

Amazingly, the Japanese captured FOOTAGE of this animal while it was still alive!! And here courtesy of the ROV cameras of SNK OCEAN CO., LTD. in Japan is the FIRST video of Astrosarkus idipii ALIVE!! The animal remains alive at an aquarium in Okinawa, Japan.

Less than SIX specimens exist in museums around the world! Not a commonly encountered animal to be sure!

Its often thought that the great undiscovered numbers of new species are likely to be small and cryptic.. Here we have not only a new species, but a new GENUS that is HUGE.

And we're STILL learning about it. What does it eat? How does it reproduce? How old is it?

First, the hero of our story...Strongylocentrotus droebachiensis- the Green Sea Urchin, which lives in the boreal North Atlantic, Arctic and North Pacific.

Like its purple and red sister species, S. droebachiensis is an ecologically important and ABUNDANT member of northern cold-water ecosystems. These urchins can voraciously devour kelp and can transform rich kelp beds to urchin barrens when densities are high. So, these urchins have an important impact on their surroundings..

Here's a recent issue of the Biological Bulletin (with photo by Rob Scheibling) that shows the crazy abundance of this species!Green Sea Urchin+Kelp+Kelp+etc..=POOP!

Green sea urchins can consume kelp at astonishing rates, consuming 454 to 530 grams (dry weight) per day (along a linear meter). Some 20% of the kelp mass consumed is digested and egested as mucus-covered fecal pellets about 1 to 3 mm in diameter. That "translates" to 91 to 106 grams (dry weight) per day.

What does that mean? Your standard nut-type candy bar weighs about 65 grams or so, So they poop close to 1.5x the weight of your standard Power Bar!!

Now imagine HUNDEDS or THOUSANDS of them doing this. Now see below:

Sauchyn and Scheibling monitored how Green Sea Urchin feces changed over 4 depth points (6, 9, 12 and 15 meters) over a 19 day site on the Atlantic coast of Nova Scotia

They looked at:

fecal composition (what the poop is made from)

pellet size (how big the poop is)

settling velocity (how long it takes for poop to settle to the ground)

Just to be clear..individual "fecal pellets" aren't that big (as indicated above only a few mm)..but you've literally got THOUSANDS of animals each putting out a substantial pile of feces all the time... After you've got a bunch they start to form big piles like this one:

The mass, density and composition of the fecal pellets begins to come apart exponentially as time goes forward!

This almost certainly means that all of the good "stuff" in feces begans to CYCLE back into the nutrient and food web segments of the ecosystem. Because corresponding to the breakdown there was also an increase in different components in "nature's nutrient recycling system":

Organic carbon

Nitrogen

Lipid and available energy content

Decrease in the Carbon to Nitrogen ratio. This one is important because it suggests that degraded sea urchin feces are an important food source for suspension feeding and deposit-feeding invertebrates (such as worms, some snails, etc.)

Settling velocity also decreases over time.

So, bottom line: Sea urchin feces breaks down and cycles BACK into the ecosystem in a BIG WAY.

Image courtesy of Dr. Robert E. Scheibling

The above #5. "Feces settling velocity decreases over time" is an important one. Density for these fecal pellets decreases, so it seems logical for their ability to settle to ground to decline as well..

The authors said it best:

As the pellets degrade and become less dense, they are likley to be transported to even deeper, less productive waters.

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!